by Craig DiLouie, LC, CLCP and C. Webster Marsh, CLCP, Lighting Controls Academy This article is based on an updated course, EE102A: Occupancy and Vacancy Sensors, at NEMA Academy. To take a quiz and get course credit, click here. INTRODUCTION Occupancy (aka, occupant) sensors monitor spaces to determine whether they are occupied or vacant, producing a control signal that can be used to automatically switch or dim lighting.